Certain configurations of gantry car washes and commercial vehicle washes require automatic frost protection. If, for example, the system works with 60 bar pressure or the undercarriage wash programme option is selected, which is fed by an external high-pressure pump and an external tank, this function is necessary. After the wash, all relevant water-bearing parts of the system are blown through and dried with compressed air. The water residues, which could cause damage in low temperatures, are then discharged via release valves. The system is controlled using a thermostat, which monitors the outside temperature.